What is Indoor Fiber Optic Cable?

Indoor fiber optic cable is engineered for installation inside buildings, including riser shafts, plenum air-handling spaces, horizontal cabling runs, and equipment rooms. Unlike outdoor cables, indoor cables use flame-retardant LSZH (Low Smoke Zero Halogen) or specialized PVC jackets to meet building fire codes and limit toxic gas emission in case of fire. OMC manufactures indoor cables in fiber counts from 1 to 144 fibers, supporting data, voice, video, and building automation networks across commercial, residential, and industrial facilities. Available constructions include tight-buffered distribution cable, breakout cable, ribbon cable, and bend-insensitive variants for tight routing in confined spaces. All indoor cables comply with international fire performance standards including IEC 60332, IEC 61034, and UL 1666.

Fire Performance Ratings Explained

Selecting the correct fire rating for indoor fiber optic cable is critical for code compliance and occupant safety. OFNR (Optical Fiber Non-conductive Riser) rated cables are tested per UL 1666 for flame propagation in vertical shafts and approved for riser applications between floors. OFNP (Optical Fiber Non-conductive Plenum) cables meet the more stringent NFPA 262 test for use in air-handling plenum spaces above drop ceilings, with low smoke and flame spread characteristics. LSZH cables comply with IEC 60332-1, IEC 60332-3, and IEC 61034 for low toxicity and low smoke emission, mandatory in many European, Asian, and Middle Eastern markets. Euroclass ratings (B2ca, Cca, Dca, Eca) provide a unified European classification system per EN 13501-6 that incorporates flame spread, heat release, smoke production, and acidity.

Construction Types and Applications

OMC offers three primary indoor cable constructions to match installation requirements. Distribution cable (also called tight-buffered) features 900µm tight-buffered fibers within a common jacket, requiring field termination with fanout kits or breakout boxes. It is the most economical choice for backbone cabling between telecommunications rooms. Breakout cable includes individually jacketed 2.0 mm or 2.4 mm subunits for each fiber, allowing direct connector termination without fanout kits, ideal for equipment room patch panel terminations. Ribbon cable uses 4, 8, 12, or 24 fiber ribbons stacked within the jacket, enabling mass fusion splicing for high-fiber-count backbones. Bend-insensitive fiber (G.657.A1/A2) versions are available for all constructions to support tight routing in cable trays and around obstacles.

Mechanical and Optical Performance

OMC indoor cables are designed for reliable installation and long service life in building environments. Tensile strength ratings during installation range from 800 N to 3000 N depending on fiber count, with long-term ratings 30-40% of installation values. Minimum bend radius is 20× cable diameter under installation stress and 10× under long-term static loading. Crush resistance is rated at 1000 N/10 cm for standard constructions and 2000 N/10 cm for armored variants. Operating temperature range is typically -20°C to +70°C for general purpose and -40°C to +75°C for extended range constructions. Attenuation specifications match the fiber type: ≤0.35 dB/km at 1310 nm and ≤0.22 dB/km at 1550 nm for single-mode, with multimode variants meeting OM3/OM4/OM5 standards.

Deployment Scenarios and Ordering

Indoor fiber optic cables serve as the backbone of enterprise LANs, data centers, FTTH building distribution, campus networks, and industrial building automation. Common deployment scenarios include vertical riser shafts connecting floor distributors, horizontal runs above drop ceilings serving work-area outlets, and inter-building connections via indoor pathways. OMC supports custom fiber counts, custom jacket colors for circuit identification, custom print legends with project-specific markings, and pre-terminated cable assemblies with connectors installed at the factory. Standard packaging is wooden reel with cable ends sealed for protection during shipping and storage. For project deployments, our team provides installation training, fusion splicing supervision, and on-site OTDR testing services to verify link performance and document the installed plant.